feat: decouple market from shared_lib, add app-owned models

Phase 1-3 of decoupling:
- path_setup.py adds project root to sys.path
- Market-owned models in market/models/ (market, market_place)
- All imports updated: shared.infrastructure, shared.db, shared.browser, etc.
- MarketPlace uses container_type/container_id instead of post_id FK

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

bp/browse/services/blacklist/category.py

@@ -1,7 +1,7 @@
 # suma_browser/category_blacklist.py
 from __future__ import annotations
 from typing import Optional
-from config import config
+from shared.config import config
 
 def _norm(s: str) -> str:
     return (s or "").strip().lower().strip("/")

bp/browse/services/blacklist/product.py

@@ -1,6 +1,6 @@
 from typing import Set, Optional
 from ..slugs import canonical_html_slug
-from config import config
+from shared.config import config
 
 _blocked: Set[str] = set()
 _mtime: Optional[float] = None

bp/browse/services/blacklist/product_details.py

@@ -1,5 +1,5 @@
 import re
-from config import config
+from shared.config import config
 
 def _norm_title_key(t: str) -> str:
     t = (t or "").strip().lower()